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Modeling of Advanced Helmholtz Resonator Liners with a Flexible Wall

Kohlenberg, Hans-Fleming and Schulz, Anita and Enghardt, Lars and Knobloch, Karsten (2023) Modeling of Advanced Helmholtz Resonator Liners with a Flexible Wall. AIAA Journal, 61 (7), pp. 3108-3118. American Institute of Aeronautics and Astronautics (AIAA). doi: 10.2514/1.J062227. ISSN 0001-1452.

[img] PDF - Postprint version (accepted manuscript)

Official URL: https://arc.aiaa.org/doi/10.2514/1.J062227


Acoustic liners are an effective way to dampen aircraft noise. Conventional single-degree-of-freedom liners consist of a perforated facesheet backed with a honeycomb structure and a rigid end plate. Their damping excels near their resonance frequency, which is antiproportional to the cavity depth (quarter-wave-resonator) or the cavity volume (Helmholtz resonator). However, this is a challenge for low-frequency noise with long wavelengths due to the limited installation space. We therefore propose a resonator in which the back cavity is divided into two cavities by a flexible plate. The aim is to combine the damping mechanisms of the Helmholtz resonator with the material damping of the flexible plate. With carefully chosen parameters, this flexible plate resonates well below the Helmholtz frequency. We derived an analytic model based on waveguide theory to predict the impedance of the resonator concept. The Helmholtz equation was solved to (numerically) determine the scattering coefficients of a channel section in which one wall is lined with the predicted resonator impedance. The predicted dissipation agreed well with experimental data from measurements at the aeroacoustic wind tunnel DUCT-R.

Item URL in elib:https://elib.dlr.de/195782/
Document Type:Article
Title:Modeling of Advanced Helmholtz Resonator Liners with a Flexible Wall
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Kohlenberg, Hans-FlemingUNSPECIFIEDhttps://orcid.org/0000-0002-6983-1545137949885
Knobloch, KarstenUNSPECIFIEDhttps://orcid.org/0000-0002-3424-0809UNSPECIFIED
Date:29 May 2023
Journal or Publication Title:AIAA Journal
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 3108-3118
Publisher:American Institute of Aeronautics and Astronautics (AIAA)
Keywords:aircraft, noise reduction, damping, liner, helmholtz resonator, coupling, flexible walls, plate vibration, material damping, impedance model, aeroacoustic
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Clean Propulsion
DLR - Research area:Aeronautics
DLR - Program:L CP - Clean Propulsion
DLR - Research theme (Project):L - Components and Emissions, L - Future Engines and Engine Integration
Location: Berlin-Charlottenburg
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Kohlenberg, Hans-Fleming
Deposited On:03 Jul 2023 09:25
Last Modified:19 Oct 2023 10:01

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